The properties of color are described, inter alia, in the following two books:
Color Science: Concepts and Methods, Quantitative Data and Formulae, Second Edition, by G. Wyszecki and W. S. Stiles, John Wiley and Sons Inc., New York, 1982; and
Principles of Color Technology, Second Edition, by F. W. Billemeyer, Jr. and M. Saltzman, John Wiley and Sons Inc., New York, 1981.
Principles of color reproduction are described in the book Principles of Color Reproduction by J. A. C. Yule, John Wiley and Sons Inc., New York, 1967.
Systems producing color images are known in the art. There are known color separation systems, which scan an original image existent on some medium, such as film or paper, and provide, on output, a digital representation of the original image. There also are known color drawing systems, typically computer based, with which an operator electronically produces an original color image, displayed to the operator on a monitor. The color drawing systems generate the digital representation of the original color image.
The digital representations thus produced are typically provided to a color printing device for reproduction of the original color images. This involves conversion of the digital representations to colorants, such as inks. However, the color of a colorant having a given digital value typically does not closely match the color of the original color image for which the color system generated the given digital value.
Therefore, systems are known in the art which modify the digital representation such that the digital value provided to the color printing device will produce the desired color.
A typical system is described in U.S. Pat. No. 4,500,919 to Shreiber. The system comprises a scanner for scanning an original and producing "appearance signals", a digital representation of the original, a monitor for displaying the appearance signals and aesthetic correction circuitry for interactively modifying the appearance signals as desired. The modified appearance signals are then provided to a colorant selection mechanism for selecting the appropriate colorant which matches the modified appearance signals.